A suspicious letter prompted the evacuation of the office of Sen. Carl Levin in Saginaw Wednesday, MLive reported.

Also, Capitol police Wednesday said they are investigating the discovery of at least three suspicious package at Senate office buildings in Washington, The Associated Press reported.

Senate Sergeant at Arms Terence Gainer said in an email that packages were dropped off at the offices of two senators, and Sen. Richard Shelby, R-Ala., said in a statement his office had received one of them, AP reported.

A third package was found in an atrium on the first floor of one of the two buildings. A person who delivered at least two of the packages was being questioned, Gainer said in the AP report.

Wednesday's incidents follow the discovery of suspicious substances in mail addressed to President Barack Obama and Sen. Roger Wicker.

The FBI said those letters are related and tested positive for the poison ricin, The Associated Press reported. They both bore Memphis, Tenn. postmarks.

A member of Levin’s staff flagged the letter and contacted authorities, MLive reported. The building that houses Levin’s office was evacuated as a precaution, according to the report.

Levin's office released the following statement from him shortly after noon Wednesday:

"Earlier today, a staffer at my Saginaw regional office received a suspicious-looking letter. The letter was not opened, and the staffer followed the proper protocols for the situation, including alerting the authorities, who are now investigating. We do not know yet if the mail presented a threat. I’m grateful for my staff’s quick response and for government personnel at all levels who are responding.”